Editing Somatic cell (section)

==Cellular aging==

In mammals a high level of repair and maintenance of cellular DNA appears to be beneficial early in life.  However, some types of cell, such as those of the brain and muscle, undergo a transition from mitotic cell division to a post-mitotic (non-dividing) condition during early development, and this transition is accompanied by a reduction in [[DNA repair]] capability.<ref>{{Cite journal |vauthors=Gensler HL |date=1981 |title=Low level of U.V.-induced unscheduled DNA synthesis in postmitotic brain cells of hamsters: possible relevance to aging |journal=Exp. Geronont. |volume=16 |issue=2 |pages=199–207 |doi=10.1016/0531-5565(81)90046-2}}</ref><ref>{{Cite journal |vauthors=Karran P, Moscona A, Strauss B |date=July 1977 |title=Developmental decline in DNA repair in neural retina cells of chick embryos. Persistent deficiency of repair competence in a cell line derived from late embryos |journal=J Cell Biol |volume=74 |issue=1 |pages=274–86 |doi=10.1083/jcb.74.1.274 |pmc=2109876 |pmid=559680}}</ref><ref>{{Cite journal |vauthors=Lampidis TJ, Schaiberger GE |date=December 1975 |title=Age-related loss of DNA repair synthesis in isolated rat myocardial cells |journal=Exp Cell Res |volume=96 |issue=2 |pages=412–6 |doi=10.1016/0014-4827(75)90276-1 |pmid=1193184}}</ref> This reduction may be an evolutionary adaptation permitting the diversion of cellular resources that were earlier used for DNA repair, as well as for [[DNA replication]] and [[cell division]], to higher priority neuronal and muscular functions.  An effect of these reductions is to allow increased accumulation of [[DNA damage (naturally occurring)|DNA damage]] likely contributing to cellular aging.